1. Field of the Invention
The present invention generally relates to an imaging device, and more particularly to a method of dynamically changing a parameter of a frame for a digital still camera or video camera.
2. Description of Related Art
Auto-exposure (AE) and auto white balance (AWB) are indispensable functions for a modern digital still camera or video camera. For example, the AE will increase brightness of a captured image in a backlight mode when a subject to be photographed is detected to be backlit. After the brightness has been increased, the subject is detected, however, not to be backlit. Accordingly, the AE will decrease or recover the brightness. The brightness increase and decrease may, unfortunately, repeat back and forth, thereby generating image flicker, which is usually called hunting phenomenon. In another example, the AWB will modify chrominance of a captured image in a nightfall mode when a subject to be photographed satisfies the nightfall mode specification or requirement. The chrominance may, unfortunately, be increased and decreased back and forth to result in the hunting phenomenon.
FIG. 1 shows a diagram illustrating the hunting phenomenon with respect to the backlight mode. In a normal situation (frame 1), the AE sets the brightness at 100%. When the backlight is detected or satisfied, the AE sets the brightness of a subsequent frame (frame 2) at 105%. After the brightness is increased to 105%, the backlight is no longer detected or satisfied, the AE thus sets the brightness of the next frame (frame 3) back to 100%. After the brightness is recovered back to (normal) 100%, the backlight is again detected or satisfied. The brightness increase and decrease in such back-and-forth manner, thereby generating image flicker or hunting phenomenon that causes annoyance to the user or viewer.
For the reason that conventional digital camera could be subjected to the hunting phenomenon, a need has arisen to propose a novel method to prevent the hunting phenomenon from happening.